Title

Author

Date of Award

2014

Document Type

Thesis

Department

Environmental and Forest Biology

Thesis Advisor

Christopher T. Nomura

Keywords

biodegradable polymers, gene knockouts, E. coli LSBJ, E. coli RSC02

Abstract

Polyhydroxyalkanoates (PHA) are one possible alternative for petroleum-based plastics that have been shown to be produced effectively in bacterial systems utilizing fatty acids. The global regulatory genes arcA and ompR are known to regulate steps involved in fatty acid transport and metabolism, making them promising candidates for research. In this study, we deleted the arcA and ompR genes in order to deregulate fatty acid uptake. To measure the effect of these deletions, copolymers were produced using recombinant E. coli and the repeating unit composition was analyzed. Residual fatty acid levels in media were also measured to determine a difference in uptake. Fatty acid transport was significantly altered in the arcA mutant, which depleted twice as much dodecanoic acid as the control strain LSBJ. The arcA mutant also showed significantly increased PHA production, measured at 30.64% (by weight) PHA, compared to 21.47% in LSBJ. Other mutants did not show significant changes. These results show that arcA is a promising mutant for increased production of PHA, and that increasing intracellular dodecanoic acid concentration has no effect on the ratio of monomers in PHA produced. This could open up new areas of research into producing plastics with very specific properties, giving PHAs a wide array of modern applications.